Electric outdoor display system



g- 1939- .1. P. TARBOX ET AL ,170,167

ELECTRIC OUTDOOR DISPLAY SYSTEM Filed July 10, 1937 3 Sheets-Sheet 1 Inventor's JOHN RTARBOX a. lubwlc; SCHIPP Q Aug. 22, 1939. J. P. TARBOX ET AL 0,

ELECTRIC OUTDOOR DISPLAY SYSTEM Filed July 10, 1937 3 Sheets-Sheet 2 Inventors JOHN P. TARBOX (L LUDWIQ S CHLFP 14 2 for/76y g- 1939- J. P. TARBOX ET AL 2,170,167

ELECTRIC OUTDOOR DISPLAY SYSTEM Filed July 10, 19s? 5 Sheets-Sheet s JOHN PTARBQX I I LU DWXQ SCHIF-F.

Patented Aug. 22, 1939 2,170,167 7 ELECTRIC OUTDOOR DISPLAY SYSTEM John P. Tarbox, Philadelphia, Pa., and Ludwig Schiff, Berlin-Lichterfelde, Germany Application July 10, 1937, Serial No. 153,068 In Germany July 11, 1936 5 Claims. (01. 178(i) rows, i. e., 12,000 photo-electric cells in all. t is Our invention relates to electric out-door display systems of the kind in which a sign board formed of a bank of electric lamps is controlled by a cell board formed of a similar bank of photo-electric cells, each cell associated with one of said lamps. Onto the cell-board, pictures, e. g., the single pictures of a cinematographic picture strip following one another, are projected. These pictures are reproduced with an essentially greater intensity and on an enlarged scale by means of the bank of lamps controlled by the cells. The board of photoelectric cells is the transmitting station, the lamp-board is the receiving station. It is possible to control several receiving stations by one transmitting station.

An object of the present invention is the provision of a system of the above type which is relatively simple, practical and reliable, and one whereby moving pictures may be produced in unlimited variety. Where the same pictures are simultaneously reproduced at several places distant one from another, e. g. along a main street, everybody passing this main street can follow this continuation of the show or act in whichever direction he is going. The invention is also applicable to the reproduction of half tone pictures.

Inasmuch as a great number of lamps are necessary to the attainment of a satisfactory amount of detail, for example 12,000 lamps for a tapestry of 120 vertical rows and horizontal rows of lamps, the wiring problem becomes: an important one. It is therefore an object of the invention to provide a system of wiring whereby the number of wires in the connecting cable may be considerably less than the number of lamps.

The invention is illustrated by way of example in the accompanying drawings in which Fig. 1 is a diagrammatic drawing of a cellboard forming the transmitting station and of a lamp-board forming the receiving station and of the connections between the photo-electric cells and lamps. Fig. 2 is a detail diagram showing the circuits associated with one complete set of related transmitting and receiving elements, and the synchronizing system.

Fig. 3 illustrates the same means as shown in Fig. 2 but in a simplified and preferred form.

Referring to Fig. 1, s is a transmitting board containing the photo-electric cells 2. While the board shown in the diagram contains only 16 lamps forming 4 Vertical and 4 horizontal rows, it is to be understood that in practice it will contain a much greater number of photo-electrio cells, e. g., vertical and. 100 horizontal a receiving or display board containing the lamps L, and which in the diagram contains likewise only 4 vertical and 4 horizontal rows, i. e., only 16 lamps in all.

According to the invention a vertical conducting bar a, b, c or d is provided by the side of every vertical row of photo-electric cells 2 and a horizontal conducting bar I, 2, 3 or 4 is provided by the side of every horizontal row of photoelectric cells z. Likewise, a vertical conducting bar a, b, c, or d is provided by the side of every vertical row of lamps L and a horizontal bar I, 2, 3, or '4' is provided by the side of every horizontal row of lamps L. At each crossing point of a horizontal bar and a vertical bar, on the board s, e. g., at the crossing point of a and 2 or of b and 2, an electric connection can be established by the neighbouring photo-electric cell 2, viz., if this cell is exposed to light. In the diagram shown it is supposed that the vertical bars connect directly with one terminal of each of the cells in the row, while the horizontal bars connect directly with the other terminals of the cells in its row. As a matter of fact there is no direct touching of the bars and the cells, the electric connection of them being effected otherwise, as shown, e. g., in Fig.2.

The verticalbars a, b, c and d are electrically connected with the grids of the electron tubes Ta, Tb, To and m respectively, while the right extremities of the horizontal bars are electrically connected with the grids of the electron tubes r1, T2, T3 and T4. The anodes of the tubes r'a, Tb, To and rd,are connected through lines a, 1)", etc., and current sources fa, fb, etc., with the bars a, b, etc., respectively, of the lamp board t. The cathodes of the tubes Ta, Tb, etc., are connected in multiple with each other and in multiple with the anodes of the tubes r1, r2, etc., by means of a common line e and by separate lines I', 2', etc. The cathodes of the tubes 11, T2, etc., are connected by means of lines I", 2", etc., to the horizontal bars I, 2', etc., respectively, of the lamp board if.

In the diagrammatic Fig. 1 only direct connections of the bars a, 1), etc., and I, 2, etc., to the grids of the perspective tubes are shown, the complete grid. circuits being omitted for the sake of simplicity. Furthermore, for the sake of simplicity there is not shown the means whereby the grids of both sets of tubes Ta, Tb, etc., and r1, r2, etc., are charged at voltages of the same (positive) Sig If a photo-electric cell isexposed to light, e. g.,

the cell lying at the crossing-point of the bars d and 3 these bars become electrically connected by the cell to a source of positive potential not shown whereupon the grids of the tubes Td and 1'3, become charged. Such voltages may be produced by the electromotive force of the photo-electric cell. The tubes Td and T3 are thereby rendered conductive. The lamp L lying at the cross point of the bars d and 3 lights up since the circuit of the battery fa has become closed through the left part of the line d", tube Td, line 6, line 3", tube T3, line 3", bar 3, lamp L, bar d, and the right part of the line 4. The conductivity of the tubes Td and T3 and therefore likewise the brightness of the lamp L corresponds to the intensity of the light to which the cell was exposed.

Generally, any lamp L may be lighted by exposing the corresponding cell 2 to light The tubes T1, T2, etc., connected with the bars I, 2, etc., respectively, act as stop valves as long as their grids are not positively charged. Likewise the tubes Ta, Tb, etc., connecting the bars a, b, etc., with bars a, b, etc., through batteries is. fb, etc., respectively, act as stop valves as long as their grids are not positively charged.

It will be seen that while it is not possible for all lamps of the receiving station to be controlled simultaneously by the corresponding cells of the transmitting station, all lamps L situated in a vertical row, e. g., at the cross-points d-l', d'2, d'-3' and d4', can be controlled simultaneously by the cells .2 situated in the corresponding vertical row of photo-electric cells. (Instead of that, all lamps L situated in a horizontal row may be controlled simultaneously by the corresponding horizontal row of photo-electric cells.) Thus while in our arrangement a scanning of the cells can and must take place, a scanning in rows is possible.

The scanning in rows, for example vertical rows, can be efiected by connecting the vertical bars a, b, c, and d one after another with the corresponding tubes Ta, Tb, To and I'd by means of a suitable distributing switch arranged to break the connection before the connection of the next vertical row has taken place. The scanning in rows can also be effected by causing the lines a", b, c" and d'f tobecome closed and opened one after another by a suitable distributing switch.

Where the vertical rows are thus scanned one after another the tubes T1, 1'2, T3 and T4 can be much smaller than the tubes Ta, Tb, To and. Ta connected to the vertical bars a, b, c, and d because only a current of a single cell is conducted through the respective horizontal bar Whereas the current conducted through the vertical bar corresponds to the sum of all partial currents conducted through all tubes connected with the horizontal bars. Since, because of the row-wise scanning, the tubes Ta, Tb, To and To are not used simultaneously they may be replaced by one single tube as indicated in Fig. 2 with the cathode of which the line e is connected. Similarly, all the sources of current fa, fb, Is and fa may be replaced by one single source of current A arranged to be connected successively with the lines a", b", c" and d" by means of a suitable distributing switch such as the commutator D.

As will be seen from the diagram Fig. 1, assuming row-wise scanning, one lamp L is definitely associated with each photo-electric cell 2. However, in order to connect the cells with their respective lamps, e. g., m vertical and n horizontal rows, not m times n lines but only m plus 11 lines need be used, e. g., if there are 120 vertical and horizontal lines not 12,000 but only 220 lines need be used.

The diagram Fig. 1 is simply illustrative of how one lamp L of a lamp-board containing m times 71 lamps may be definitely associated with each photo-electric cell 2 of a cell board containing m times 12 cells, with only m plus n connecting lines used.

In Fig. 2 is shown a diagram of the circuit which may be used for a single photo-electric cell a lying at the crossing point of the bars it and 8 and its associated lamp L lying at the cross point of bars 70' and 8'. A small control tube R is connected in series with each single lamp, In the drawings this control tube is connected with the bars k and 8 Alow current source F, is provided for the control circuit at the transmitting station While a strong current source is provided at the receiving station for feeding the lamps L.

In the embodiment shown the vertical rows of the picture points or cells 2 are scanned rowwise, one vertical row at a time. All vertical bars a, b, c k are connected with the grid G of a singletube T. The grid G is biased (preferably negative) by means of the battery B and a resistance W.

The bar 8 is connected with the grid Gs of the tube T8, the grid G8 being biased, preferably negatively, by means of a battery Ba and resistance W8. The tubes T and T8 are connected in series, the cathode K of the tube T being connected with the anode A8 through the multiple line 2 and the individual line B", and similar individual lines associated with other horizontal rows. The anode A of the tube T is connected with the positive pole of the battery F the negative pole of which being connected with the bar k4 through the commutator to be later described, the bar k4 being connected to the line is. The cathode K3 is connected with the bar 8 through the line 8".

The cathode of the cell .2 associated with the cross-point of the bars k and 8 is connected with the condenser plate .r+ While the anode is connected through the battery Bz with the condenser plate :t of a condenser :10. The line conductor connected to the plate :c is earthed through a resistance WZ. The two condenser plates .r+ and m are arranged to be bridged across the resistance WX through a multiple bridging circuit ICx-y common to the photo-electric cells 2 of the vertical roW associated with bar is, the bridging circuit being arranged to be closed at the proper time through the commutator switch arm N. Upon closure of the bridging circuit the condenser plate x+ becomes connected with the line L; which is connected on the one hand with the bar is through a condenser Pk and on the other hand with the bar 8 through a condenser Pa. As long as the bridging circuit is opened, as shown in Fig. 2, the plate an of the condenser a: is charged. This charge is effected during the time the board of cells z is exposed to the light of a picture projected on it, e. g., a picture from a cinematographic picture strip. The amount of charge depends on the intensity of the light thrown onto the cell a and is proportional to it. When the bridging circuit is closed the condenser 22 becomes discharged suddenly and a positive voltage is transmitted through condenser Pk to the grid G of the tube 1' and through condenser P8 to the grid GB of the tube T8. Thereby both Cir tubes r and r8 become conductive and current from the source F is conducted through them and through the two bars 8' and lo of the receiving station, an electric conduction being made at the same time between the bar 7c and the anode A of the tube r through the bar lo; and switch arm M of the commutator switch.

The storage of electrical energy is effected simultaneously in all condenserszc belonging to all of the cells of the entire bank of receiving cells. In each condenser belonging to any cell of the cell-board the voltage produced by a picture, e. g., by a single cinematographic picture projected onto the cell board corresponds to the intensity of the light thrown on the respective picture point.

Each of the receiving picture point units consisting of the parts Bz, Lz, Pk Pa, .16, WK, Wz associated with a photo-electric cell z constitutes a small compact unit which may be cheaply manufactured in mass production. 12,000 such units would be required for a cell-board of 120 vertical and 100 horizontal rows.

The discharging of the condensers :c of the cell-board takes place row-wise, so that the different vertical rows are discharged one after another, all condensers of the same vertical row, e. g., the condensers at the side of the bar is, being discharged simultaneously.

In the example shown in Fig. 2, the simultaneous discharge of all the condensers :c of a vertical row, e. g., those associated with the photo-electric cells 2 at the side of the bar is, followed by a similar discharge of the condensers x of the remaining vertical rows in succession, as well as the synchronous closure of the vertical conductors 70', etc., of the receiver with the nega tive terminal of the source F, is effected by the commutator switch arms N and M, respectively.

The commutator switch comprises a shaft D supported by a bearing C and driven by means of a pulley or a toothed wheel E at the number of revolutions per second corresponding to the number of pictures following one another in a second. The cylindrical commutator disk H is rigidly fixed at the righthand bearing, coaxially with the shaft D. The cylindrical commutator disk I is rigidly fixed at the lefthand bearing coaxially with the shaft D. Metal sectors 114,124, 04 k4 are mounted in a sector of the outer surface of the disk H insulated one from another. The sectors are of an angular extent corresponding to the duration of the dark pause between successive pictures of the synchronously driven cinematographic strip. These metal sectors are connected with the bars a, b, c k of the receiving station by lines a", b, c k joined in a cable. Atcorresponding angular positions metal sectors can, bxi, X1 -kxi are mounted in the outer surface of the disk I insulated one from another. These metal sectors are connected with the bus bars (1x,bx, Cx kx respectively. A lever M is rigidly mounted on the shaft D. A Contact spring M fixed on the lever M slides on the outer surface of the disk H during the rotation of the shaft D. Similarly a lever N fixed on the shaft D carries a contact spring N which slides on the outer surface of the disk I during the rotation of the shaft D. The two contact springs M and N are electrically connected with the frame C. The negative pole of the source of current F is connected with the frame C, the positive pole being connected with the anode A. Further, the bus-bar 'y-is connected with the frame C. During a dark pause following a single picture the spring N slides successively over the metal sectors an, bxl, Cxl and at the same time the spring M slides successively over the metal sectors 14,174, 04 Therefore, at the same moment at which a vertical row of condensers ar, e. g., of the condensers lying-at the side of the bar is, is discharged the electrical connection with the corresponding bar, e. g., the bar is" of the receiving station is made.

The receiving station is connected with the transmitting station exclusively by a cable containing the lines a", b, c Jk and by a cable containing the lines I", 2", 3" 8" or by a common cable containing all these lines. As mentioned above, each lamp L of the lamp-boardisconnected in the anode circuit of a controlling tube R. All lamps are fed by a dynamo O the positive pole of which is connected with a plate S and the negative pole of which is connected with a plate T. One terminal of all the lamps is connected with the plate T and is thereby connected with the negative pole of the dynamo O. In Fig. 2, only the lamp L is shown lying at the crossing point of the bars k and 8' with the anode circuit of the tube R connected with it in series. The grid GR, of the tubeR is connected with the bar k by the line 705. The anode AR, is connected with the plate S and so with the positive pole of th'e'dynamo O by the line SR. In the same manner the grids of all tubes R lying in a. horizontal row are connected with the corresponding horizontal bars I, 2, 3 and the cathodes of all tubes R lying in a vertical row are connected with the corresponding vertical bar a, b, c

Each lamp L and its local individually associated circuits. and apparatus elements including the tube R, forms a small compact unit which may be cheaply manufactured in mass production.

The grid GR, of each single tube R associated with any lamp L of the lamp board is so Well insulated that it retains a voltage impressed upon it during a certain space of time. The device serving for this purpose is not a. matter of this application and is therefore not illustrated. During this space of time the tube R remains conductive until it loses its positive voltage by earthing or by a negative voltage impressed on it. If the necessary'high ohmic resistance may be inserted across cathode KR, and grid GR.

The mode of operation is the following:

During the time in which a single picture, e. g., of a cinematographic picture strip is projected onto the cell board the condenser x of each. cell becomes charged to an amount corresponding to the intensity of light of the respective picture point. During the following dark interval a further charging of the condensers a: does not take place. During the dark interval condensers m become discharged row-wise, one row after another; the commutator shaft D being rotated during the dark interval synchronously with the movement of the picture strip to carry the contact springs N and M over their respective banks of segments. corresponding bars of the receiving station is made synchronously with the scanning of the vertical rows of photo-electric cells 1', so that, e. g., when the row of condensers x lying at the side of the vertical bar k is discharged, a current impulse is sent from the source of current F through the tube 1', through all tubes 1'1, 1'2, r3 1'8, lying at the side of bar k, through the lines I", 2", 3" 8", through the bars Thus electrical connection with the v I, 2, 3 8, through the lines is, 25, 35 85, through the grids GR and the cathodes KR of all tubes R connected in series with the lamps lying at the side of the bar is, through the bar It, through the line It, through the metal sector k4, through the spring M, and through the frame C to the negative pole of the source of current F. Thereby the grids GR, of the tubes R belonging to the lamps L lying at the side of the bar k are charged each to an amount corresponding to the intensity of light which was thrown on the respective picture point during the preceding picture period. The preceding picture is thus made visible on the lamp board. At the end of the picture period all grids GR, become discharged and ready for another charging. Therefore, the feeding of the lamps takes. place during about the whole duration of a single picture.

Fig. 3 illustrates a modified form of the device shown. in Fig. 2.

Owing to the fact that the condensers a: of the cells 2 are discharged one vertical row after the other, and that the single cells of one vertical row of cells (e. g., of the vertical row lying at the side of the bar it) are connected by separate lines and through separate tubes (11, 1'2, T3 to their associated lamps L, not only the tube T which functions as a circuit closing switch but some other parts can be dispensed with, as shown in Fig. 3. For example, the bar k may be omitted since its function of determining which row of condensers a: shall be discharged is fulfilled by the bar kt. Elimination of the tube 1* elminates necessity for the condensers Pk and P8, and the resistance We.

It is to be understood that the terms vertical row and horizontal row are used herein to designate any arrangement of two coordinated groups each containing one element of each of the other groups such that each element is contained in both groups, and that these terms where used in the claims are intended to include such equivalents.

While herein certain specific embodiments of the invention have been shown and described for the sake of disclosure, it is to be understood that the invention is not limited to such specific embodiments but contemplates all such modifications and variants thereof as fall fairly within the scope of the appended claims.

What is claimed is:

1. An electric outdoor display system comprising a bank of lamps arranged in coordinate vertical and horizontal rows, each horizontal row containing one lamp in each vertical row and each vertical row containing one lamp in each horizontal row, electrically responsive control elements one for each lamp arranged in coordinate vertical and horizontal rows corresponding to the rows in the lamp bank, a bank of photoelectric cells one for each control element arranged in coordinate vertical and horizontal rows corresponding to the rows in the lamp bank, a

condenser for each photo-electric cell arranged to be charged thereby, a plurality of horizontal group conductors one for each group of con densers belonging to a horizontal row of photoelectric cells, a group relay device for each horizontal row of cells having its control circuit operatively connected with the group conductor of that row for control of said relay over said conductor, an individual conductor for each relay operatively connecting one output terminal of its relay with one terminal of each of all the control elements in a horizontal row corresponding to the horizontal row of cells associated with said relay, a common return conductor for each vertical row of control elements, a commutator switch arranged to connect the other output terminals of all the relays at one time to each of said return conductors one at a time in sequence, and means for simultaneously discharging all the condensers of a vertical row each into its respective group conductor one row at a time in sequence and in synchronism with the sequential connection of the said other output terminals to the return conductors of corresponding vertical rows of control elements.

2. An electric outdoor display system comprising a bank of lamps arranged in rows, a row of electrically responsive control devices for each row of lamps, having a control device for each lamp, a bank of photo-electric cells arranged in rows one row for each row of control devices each row of photo-electric cells having a cell for each control device in the corresponding row of control devices, a condenser for each photo-electric cell arranged to be charged thereby, a plurality of group conductors each associated with a group of condensers comprising one condenser of each row of photo-electric cells, a group relay device for each group conductor having its control circuit operatively connected with its group conductor for control thereover, an individual conductor for each relay connecting one output terminal of its relay with one terminal of each of a group of control devices, said group comprising one control device of each row of control devices, a common return condenser for each row of control devices connected to the other terminal of each of the control devices in its associated row, a commutator switch arranged to connect the other output terminals of all the relays at one time to each of said return conductors one at a time in sequence, and means for simultaneously discharging all the condensers of a vertical row each into its respective group conductor one row at a time in sequence and in synchronism with the sequential connection of the said other output terminals to the return conductors of corresponding vertical rows of control devices.

3. An electric outdoor display system comprising a bank of lamps arranged in coordinate ver tical and horizontal rows, a bank of photo-electric cells one for each lamp similarly arranged, a triode lamp control relay for each lamp, a condenser for each photo-electric cell arranged to be charged thereby, a group conductor leading from, each group of condensers associated with a given horizontal row of cells, a triode group relay for each horizontal row of cells having its control circuit operatively connected to the group conductor associated with said horizontal row of cells, each group relay having one of its output terminals connected in multiple to one input terminal of all the lamp relays in a horizontal row, a common return conductor for each vertical row of lamp relays connected in multiple with all the other input terminals of all the lamps in its vertical row, a sequence switch arranged to connect all the other output terminals of all the group relays at one time to each of said return conductors one at a time in sequence, and means for simultaneously discharging all the condensers in a vertical row each into its respective horizontal group conductor, one row at a time in sequence, and in synchronism with the sequential connection of the said common return conductors of corresponding vertical rows of lamp relays.

4. The system as claimed in claim 3 including intermittent exposure means for intermittently exposing the photo-electric cells to a light image with intermediate periods of darkness, synchronized with the condenser discharge means for effecting the discharge of all the condensers only during a dark period.

5. A system as claimed in claim 3 in which a resistance is connected in series with the discharge circuit of each condenser.

JOHN P. 'IARBOX.

LUDWIG SCHIFF. 

